According to James McAvoy, X-Men: Dark Phoenix underwent lengthy reshoots to change the film’s ending after it was discovered that it bore a striking resemblance to another superhero film that was also in production.

However, James McAvoy, who plays a conflicted Charles Xavier in Dark Phoenix, says there’s more to it than that. Talking about the reshoots, McAvoy admits to Yahoo Movies UK: “The end [of Dark Phoenix] changed a hell of a lot.”

“The finale HAD to change. There was a lot of overlap and parallels with another superhero movie that came out... a while ago. And we had no idea that we were...”

“We were basically trawling through the source material it seems,” finishes McAvoy.

Michael Fassbender and James McAvoy spill the beans on those Dark Phoenix reshoots.

The duo wouldn’t be drawn on which rival superhero movie they were referring to, leaving it wide open to speculation.

Looking at the release schedule from Dark Phoenix’s wrap date in October 2017 to now, there have been 11 major live action DC or Marvel superhero movies in cinemas during that period: Thor: Ragnarok, Justice League, Black Panther, Avengers: Infinity War, Deadpool 2, Ant-Man and the Wasp, Venom, Aquaman, Captain Marvel, Shazam!, and Avengers: Endgame.

Of those films, only Thor: Ragnarok, Infinity War, Captain Marvel, and Endgame have had lengthy space-set sequences that could potentially clash with Dark Phoenix’s original climax. Interestingly, Disney’s acquisition of Fox - the studio behind Dark Phoenix - was first reported in November 2017, during the post-production phase on the new X-Men film.

The planned merger might have led to a “show and tell” meeting, with execs at the two rival superhero studios at Fox and Disney (Marvel Studios) looking over each other’s upcoming slates to ensure there were no clashes between their films. But which Marvel Studios film specifically might have been trawling “through the same source material”? We think there are two likely contenders.

Simon Kinberg, director of Dark Phoenix, previously stated they’d also changed the VFX around Jean Grey’s (Sophie Turner) transformation into Dark Phoenix to make it more “cosmic” and less “flamy”.

Flame on: Early Dark Phoenix publicity stills showed a much more fiery look for Jean Grey. This has been changed in the final film for something very different. (20th Century Fox/Marvel Studios)

This suggests the clash may have been with Captain Marvel, which saw Brie Larson’s Carol Danvers assuming her superhero abilities with a flame-like aura around her. That film also had a space-set climax, with Captain Marvel seeing off Ronan’s Kree spaceship in earth’s orbit.

Another contender could be Infinity War. In the comics, The Dark Phoenix Saga - written by Chris Claremont with art by John Byrne - published in 1980, climaxes in space with a battle between the X-Men and the Shi'ar Imperial Guard on the “Blue Area of the Moon”. It may have been very similar to the Titan-set battle in the 2018 Avengers film between Thanos and Iron Man, Spider-Man, and the Guardians of the Galaxy.

A still from the newly retooled Dark Phoenix ending (20th Century Fox)

Regardless of the reasons behind the change, the cast all agree the film is better off for it.

“I think it’s so much better for the reshoots,” says Sophie Turner.

“It was just one of those things that was where the third act... you watch the first two acts and the third act just didn’t feel cohesive. We went back and we redid all of the third act, pretty much, and it was such a good decision.

Jessica Chastain, who plays a mysterious shape-shifting alien in Dark Phoenix, says she found the script changes challenging.

“My character changed a lot,” explains Chastain.

“Which is an interesting thing, because i’m not playing someone from the comics, so it was almost like everyday trying to figure out ‘who am I?’, the mystery of who is this character. And then understanding that also with the reshoots realising it was changing again.